Problem: $\dfrac{6}{3} - \dfrac{5}{4} = {?}$
$ = {\dfrac{6 \times 4}{3 \times 4}} - {\dfrac{5 \times 3}{4 \times 3}} $ $ = {\dfrac{24}{12}} - {\dfrac{15}{12}} $ $ = \dfrac{{24} - {15}}{12} $ $ = \dfrac{9}{12}$